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I Jk Agriculture 



Canada 

Research Direction generate 
Branch de la recherche 



Contribution 1983-21 E 




Ten-year irrigated rotation U. 
1911-1980 




Canada 



The map on the cover has dots representing 
Agriculture Canada research establishments. 



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Ten-year irrigated rotation U. 
1911-1980 



S. DUBETZ 
Research Station 
Lethbridge, Alberta 



Research Branch 
Agriculture Canada 
1983 



Copies of this publication are available from: 

Mr. S. Dubetz 

Soil Science Section 

Research Station 

Research Branch, Agriculture Canada 

Lethbridge, Alberta 

T1J 4B1 

Produced by Research Program Service 

©Minister of Supply and Services Canada 1983 



CONTENTS 

Acknowledgements i 

Summary/ Resume ii/iii 

History and general progress 1 

Soil sampling and soil analyses 5 

Results and discussion 6 

Crop yields 6 

Soil analyses 8 

References 11 



ACKNOWLEDGEMENTS 

The late Dr. W. H. Fairfield, first superintendent of the Lethbridge 
Experimental Station, started rotation U. The late Dr. Frank T. Shutt, 
Dominion Chemist, Ottawa, established the practice of taking soil 
samples at the beginning of each rotation cycle. The rotation 
continued under the supervision of Drs. A. E. Palmer and K. W. Hill 
until 1951. 

The author is indebted to the late Dr. H. J. Atkinson, Head of the 
Soil Chemistry Unit, Ottawa, under whose supervision the first soil 
analyses were performed in 1951. 

Appreciation is extended to the farm foremen and to the numerous 
plotmen and technicians who performed the field and laboratory work. 
Thanks are also extended to many summer students, some of whom later 
attained eminence in agricultural research, for their interest and 
care in the continued maintenance of the rotation. 

The author is indebted to Dr. J. A. Robertson of the University of 
Alberta for his review and helpful suggestions. 



11 



SUMMARY 



Started in 1911, Rotation U is believed to be the oldest continuous 
irrigated crop rotation in North America. It occupies ten 0.4-ha 
plots and consists of six years of alfalfa, wheat, oats, barley, and 
sugar beets. Each plot receives barnyard manure at 67 t/ha in a 10- 
year cycle, and three crops (Alfalfa 1, Alfalfa la, and Sugar beets) 
receive 11-48-0 fertilizer at 112 kg/ha each year on the south half of 
the plots. The rotation has provided the following information: 

• Crop yields have continued to increase with time. The regression 
coefficients of sugar beets, barley, hard red spring wheat, and 
oats on advancing years are 0.250, 0.061, 0.020, and 0.034 t/ha/yr . 

• The record crop yields are as follows: Sugar beets 62.97, alfalfa 
14.07, barley 8.62, hard red spring wheat 4.97, and oats 6.99 t/ha. 

• Alfalfa was plagued with diseases for about three decades, but the 
problem has now been largely overcome. 

• The pH in the top 15 cm of soil increased gradually from 7.1 to 
7.6 during the first 60 years and appears to have stabilized. 

• Organic matter decreased slightly from 2.62 to 2.25% in the top 15 
cm of soil but increased from 1.50 to 2.07% in the 15- to 30-cm 
layer. 

• Total nitrogen increased from 0.18 to 0.20% in the 0- to 15-cm 
layer and from 0.13 to 0.18% in the 15- to 30-cm layer. 

• Available phosphorus has remained relatively low (10 ppm) in the 
0- to 15-cm depth of the unfertilized plots but has increased to 
15 ppm in the plots that received fertilizer. 

• Exchangeable potassium decreased from 376 to 306 ppm in the 0- to 
15-cm layer and from 272 to 225 ppm in the 15- to 30-cm layer but 
critical levels have not been reached. 

• The improved productivity of the soil is attributed to the use of 
barnyard manure, alfalfa, and fertilizer. 

• The rotation will continue to provide new information relative to 
the permanency of irrigated agriculture for decades to come. 



Ill 



RESUME 



Amorcee en 1911, la Rotation U est consideree comme la plus ancienne rotation 
continue de cultures irriguees en Amerique du Nord . Elle occupe dix parcelles 
de 0,4 ha chacune et se compose de cultures de luzerne, de ble, d'avoine, 
d'orge et de betterave a sucre reparties sur six ans . Chaque parcelle recoit 
du fumier d'etable a raison de 67 t/ha dans un cycle de 10 ans et trois 
cultures (luzerne 1, luzerne la et betterave a sucre) recoivent de l'engrais 
11-48-0 a raison de 112 kg/ha chaque annee dans la moitie sud des parcelles. 
Le regime cultural a permis d'obtenir des donnees suivantes: 

• Lesrendements ont continue d ■ augmenter au fil du temps. Les coefficients 
de regression de la betterave, de l'orge, du ble vitreux roux de printemps 
et de l'avoine au fil des ans sont de 0,250, 0,061, 0,020 et 0,034 t/ha par 
annee . 

• Les rendements maximaux s ' etablissent comme suit: betterave 62,97, 
luzerne 14,07, orge 8,62, ble vitreux roux de printemps 4,97 et avoine 
6,99 t/ha respectivement . 

• La luzerne a ete assaillie par des maladies pendant trois decennies 
environ, mais le probleme est en grande partie resolu maintenant . 

• Le pH dans les 15 premiers centimetres du sol est passe graduellement 

de 7,1 a 7,6 au cours des 60 premieres annees et semble s'etre stabilise 
depuis . 

• La teneur en matiere organique a legerement diminue de 2,62 a 2,25% 
dans les 15 premiers centimetres, mais s ■ est accru de 1,5 a 2,07% dans 
la couche de 15 a 30 cm. 

• L' azote total est passe de 0,18 a 0,20% dans la couche de a 15 cm 
et de 0,13 a 0,18% dans celle de 15 a 30 cm. 

• La teneur en phosphore assimilable est demeuree relativement faible 
(10 ppm) dans les 15 premiers centimetres du sol des parcelles qui 
n'ont pas recu d'engrais, mais a atteint 15 ppm dans les parcelles 
fertilisers . 

• La teneur en potassium exchangeable a baisse de 376 a 306 ppm dans la 
couche de a 15 cm et de 272 a 225 ppm dans celle de 15 a 30 cm, 
mais les concentrations seuils n'ont pas ete atteintes. 

• La productivity accrue du sol est due a 1 'utilisation du fumier, de 
la luzerne et de l'engrais. 

• La rotation ne cessera pas de fournir de nouvelles donnees sur la 
permanence de 1 'agriculture irriguee dans les decennies a venir. 



HISTORY AND GENERAL PROGRESS 

The Lethbridge Research Station was established in August, 1906, as 
the sixth facility of the Experimental Farms Service. It originally 
consisted of 162 ha of unbroken prairie land that was donated to the 
Government of Canada by the Alberta Railway and Irrigation Company. 
During the fall of the first year, 4 ha of land were broken and by the 
following summer an additional 60 ha were put to the plow. The first 
crops were grown in 1908. Cereals, alfalfa, and potatoes were grown 
during the first few years. Alfalfa hay was a major cash crop then as 
it was required for the many horses and mules that were used in rail- 
road and irrigation works construction at the time. 

Rotation U, a 10-year rotation comprised of ten 0.4-ha plots, was begun 
in 1911. It is believed to be the oldest continuous irrigated rotation 
in North America. The original crop sequence was as follows: six 
years of alfalfa, then one year each of potatoes, wheat, oats, and 
barley. Eleven tonnes of manure (27 t/ha) were applied annually in 
the fall to the plot growing the 5th year of alfalfa. Thus, each plot 
received 11 tonnes of manure once in 10 years. The rotation 
progressed unchanged until 1923. 

Typical of land preparation and cultural practices that were in use is 
the following information gleaned from the 1913 records concerning the 
potato crop that was grown in the rotation in that year. 

In September, 1912, the plot was plowed 8-10 cm deep, packed 
and double-disced with a four-horse-team. In the spring of 
1913, the plot was plowed 20-23 cm deep and harrowed twice. 
Six hundred and seventy kilograms of potatoes (cv. Gold Coin) 
were planted on May 20 and 21 with a two-horse planter in 
71-cm rows with tubers spaced 35 cm apart. It took one man 
three days to carry out the first hoeing in mid-June but the 
second hoeing required only one day. The crop was cultivated 
on June 17 and July 5, and was hilled and flood-irrigated on 
July 14. On July 18, the crop was sprayed with 0.4 kg of 
Paris Green, and on July 28 with 0.3 kg. On August 22, one 
man (an inmate from the nearby Provincial Gaol) pulled weeds 
out of the crop. The potatoes were harvested on October 2 and 
3 with a four-horse digger. A yield of 14,392 kg of marketable 
tubers and 1050 kg of unmarketable tubers was realized from 
the 0.4-ha plot. 

By 1920, the rotation had completed its first cycle and had become 
fully established. Yields fluctuated between years but the 50.85 t/ha 
of potatoes harvested in 1912, 4274 kg/ha of hard red spring wheat in 
1914, 4436 kg/ha of oats, and 13.66 t/ha of alfalfa in 1916, attested 
to the high yields that were attainable with irrigation. With the 
impending re-establishment of the sugar beet industry (a factory was 
opened at Raymond in 1925) , sugar beets were substituted for potatoes 
in 1923. This was the only change in crops made in the rotation. 



- 2 - 



By 1924, alfalfa yields began to decrease and continued to decline 
into the third decade as evidenced in the five-year average yields in 
t/ha of fourth-year alfalfa. 

1913-17 1918-22 1923-27 1928-32 

9.39 10.04 6.88 6.09 

Because it was thought that phosphorus was lacking in the soil, in 
1933 triple superphosphate (0-43-0) at 110 kg/ha was applied to the 
south half of each of three plots, viz., first-year alfalfa, fourth- 
year alfalfa, and sugar beets. When the manufacture of triple 
superphosphate was discontinued in western Canada, ammonium phosphate 
(11-48-0) fertilizer was substituted in 1938 and has been used since. 

The benefits of the phosphorus fertilizer were soon apparent on the 
alfalfa and sugar-beet crops as shown below in the 5-year average 
yields in tonnes/ha. 





1933- 


-37 


1938- 


-42 




Fertilizer 


No 
fertilizer 


Fertilizer 


No 
fertilizer 


Alfalfa - fourth-year 
Sugar beets 


8.00 
41.19 


5.26 
35.80 


9.77 
43.43 


5.67 
36.31 



In 1942, the manure application was increased from 27 t/ha to 67 t/ha. 
Starting that year, a 33.5-t/ha application was applied to two of the 
ten plots. Thus, in the course of 10 years each plot (0.4 ha) received 
27 tonnes of manure. The rate of manure was increased to replace the 
nutrients removed by the crops, particularly those of the unfertilized 
half of the plots. 

About 1939, bacterial wilt spread into southern Alberta and infected 
the alfalfa plots on Rotation U. The cultivar Grimm, grown at the 
time, was very susceptible to the disease. Periodic surveys of the 
plots showed that about half of the plants were infected with the 
disease by the fourth year and in the sixth year almost 90% of the 
plants were infected (Peake and Cormack, 1955). Consequently, alfalfa 
yields, particularly those of the fourth, fifth, and sixth years, 
declined rapidly during the 1940' s. Yields of less than 2 t/ha were 
recorded from some plots. Crown bud rot, a complex disease of alfalfa, 
also made its appearance about this time and contributed to depressed 
yields. As a result of the declining alfalfa yields, a major change 
in the cropping sequence was made in 19 51. The new sequence, which 
still maintained the manure and fertilizer treatments, follows. 



Crop 



Treatment 



Wheat and alfalfa 
Alfalfa la 
Alfalfa 2a 
Alfalfa 3a 
Barley 

Oats and alfalfa 
Alfalfa 1 
Alfalfa 2 
Alfalfa 3 
Sugar beets 



none 

11-48-0 at 110 kg/ha to south half 

manure at 33.5 t/ha 

none 

none 

none 

11-48-0 at 110 kg/ha to south half 

none 

manure at 33.5 t/ha 

11-48-0 at 110 kg/ha to south half 



After three years, the new alfalfa series (1, 2, and 3) became 
established, and the other alfalfa series (la, 2a, and 3a) continued 
as part of the previous 6-year series. 

In 1959, the cultivar Vernal, which showed some resistance to bacterial 
wilt, was substituted for Grimm. In 1971 the last change in cropping 
sequence was made. The positions of wheat and sugar beets were inter- 
changed to facilitate early cultivation of beets without interference 
from alfalfa root remnants. Also, starting in that year, alfalfa was 
seeded without a companion crop and one cut of hay was taken. Two 
cuts of hay are normally taken with established alfalfa. Finally, in 
1974, the cultivar Trek, highly resistant to bacterial wilt and to the 
alfalfa stem nematode, was used. Thus, every effort was made to 
improve the alfalfa yield and in the 1970 's the yields (t/ha) did 
improve as shown below. 









1966- 


-70 




1971- 


-75 




1976- 


-80 








No 






No 






No 






Fert. 


fert. 


Fert. 


fert. 


Fert. 


fert. 


Alfalfa 


2a 


7 


.39 


6.16 


9 


16 


7.37 


11 


.67 


9.27 


Alfalfa 


3a 


8 


.29 


7.62 


8 


.15 


4.79 


10 


.37 


8.33 



The disease problems that plagued alfalfa for three decades have been 
largely overcome with changes in management practices and with the 
introduction of disease-resistant cultivars. As a consequence of the 
improved recovery of the rotation, alfalfa yields and N2 fixation 
should continue to increase, and better yields as well as improved 
soil properties should result in the decades ahead. 



Throughout the years, sugar beet tops have been returned to the land 
but the straw from the cereal crops has been hauled off the plots. 

Surface irrigation was practised until 1966. Each surface application 
consisted of 10 to 15 cm of water and, in most years, all of the plots 
were irrigated after harvest in the fall. The number of irrigations 



- 4 - 



during the growing season varied, depending on the crop and the amount 
of precipitation. Generally, sugar beets received 3 to 4 irrigations, 
alfalfa 2 to 3 irrigations, and the cereal crops 1 to 2 irrigations. 

The quality of irrigation was likely improved with the introduction of 
sprinklers in 1967. The sprinkler method used smaller amounts of water 
and provided a more uniform application. In general, irrigation was 
practised to maintain soil water in the upper half of the available 
range. 



- 5 - 



SOIL SAMPLING AND SOIL ANALYSES 

The soil is classified as an Orthic Dark Brown Chernozem (Lethbridge 
series) developed on alluvial lacustrine parent material. The texture 
of the surface 30 cm of soil is generally a loam (48% sand, 32% silt, 
and 20% clay) . 

In October, 1911, the first soil samples were taken from the 0- to 15- 
and 15- to 30-cm depths from all plots. Similar samples were taken in 
1922. Starting in 1933, samples were taken from both halves (north 
half, unfertilized; south half, fertilized since 1932) from each plot 
for the two depths. This was repeated in 1941 and 1951. In 1953, two 
additional depths (30-60 and 60-90 cm) were taken and analyzed for 
total N and organic matter at Ottawa, but no further analyses were 
performed on these samples and they were not returned to Lethbridge. 
In 1961 and 1971, samples were taken from 0- to 15-, 15- to 30-, 30- 
to 60-, and 60- to 90-cm depths from both halves of all plots. 
Finally, in 1981, the depth of sampling was increased to 180 cm, the 
last four depths composed of 30-cm layers. 

All of the samples from 1911, 1922, 1933, 1941, and 1951 were analyzed 
in 1951 for pH, total N, loss on ignition, exchangeable K, and 
available P by the Science Service, Soil Chemistry Unit, at Ottawa. 
Data from only three of the ten plots were recorded for 1933. The 
results of the Ottawa analyses were reported by Hill (1951) and Dubetz 
(1954) . After analysis the remaining soils (except those of 1933) 
were returned to Lethbridge where they were stored. Because data from 
only three plots of the 1933 samples were reported and the samples 
were not available for further analyses, none of the 1933 data are 
presented. 

During the 70-year period, some methods of analyses had changed which 
made direct comparisons inappropriate. For example, on samples taken 
between 1911 and 1951, organic matter was estimated by loss on ignition 
(450°C for 3 h) , and available phosphorus (P) was analyzed by the 
K2CO3 method. Consequently, these samples were analyzed by the 
newer methods (K 2 Cr 2 7 method for organic matter and NaHC0 3 
method for P) in 1981. Also in 1981, the 1961, 1971, and 1981 soil 
samples were analyzed for pH, electrical conductivity, nitrogen, O.M. , 
available P, and exchangeable K. The following methods were used: 

1. pH and electrical conductivity - saturated paste 

2. Nitrogen - Kjeldahl method (Association of Official 

Agricultural Chemists, 1970) 

3. O.M. - K 2 Cr 2 7 method, described by Walkley and Black 

(1934) 

4. Available P - sodium bicarbonate method (Olsen et al., 1954) 

5. Exchangeable K - IN ammonium acetate method as outlined in 

the Association of Official Agricultural Chemists (1970) 



- 6 ~ 



RESULTS AND DISCUSSION 

Crop Yields 

The average yields of crops grown in the rotation from 1911 to 1950 
(prior to the revision) are shown in Table 1 and the yields from 1911 
to 1980 are shown in Table 2. The yields of most crops presented in 
Table 2 are higher than those in Table 1, which indicates that crop 
yields improved with time. Regression coefficients calculated for the 
period 1911 to 1980 show that barley, wheat, and oats increased on 
average 0.061, 0.020, and 0.030 t/ha/yr (1.13, 0.30, and 0.89 
bu/ac/yr) . Sugar beets have increased on average by 0.25 t/ha/yr (0.11 
tons/ac/yr) during the 58 years that they have been grown. Similar 
comparisons for alfalfa are more difficult to obtain because of the 
many years the crop was plagued with bacterial wilt and other diseases. 



Table 1. Cropping sequence, treatments, and long-term yields of 
crops grown on Rotation U from 1911-1950 



All yields in tonnes/ha 



Yields of cereals 
in bu/acre, alfalfa and 
sugar beets in tons/acre 







Fert. 


Unfert. 


Fert. 


Unfert. 




1933-1950 


1911-1950 


1933-1950 


1911-1950 


Oats 




4.08 


3.71 


107.2 


97.5 


Barley* 




3.95 


3.44 


73.5 


63.9 


Sugar beets 


42.11 


34.65 


18.8 


15.47 


Wheat 




3.96 


3.52 


58.9 


52.4 


Alfalfa 


1 + 


6.45 


5.35 


2.88 


2.39 


Alfalfa 


2* 


9.27 


6.88 


4.14 


3.07 


Alfalfa 


3 


8.44 


7.19 


3.77 


3.21 


Alfalfa 


4 + 


8.31 


7.12 


3.71 


3.18 


Alfalfa 


5 


6.36 


6.65 


2.84 


2.97 


Alfalfa 


6 


4.66 


6.63 


2.08 


2.96 



*Barnyard manure at 33.5 t/ha to entire plot. 
11-48-0 at 110 kg/ha to south half of plot. 



- 7 - 



Table 2. Cropping sequences, treatments, and long-term yields of 
crops grown on Rotation U from 1911-1980 



All yields in tonnes/ha 



Yields of cereals 
in bu/acre, alfalfa and 
sugar beets in tons/acre 





Fert. 


Unfert. 


Fert. 


Unfert. 




1933-1980 


1911-1980 


1933-1980 


1911-1980 


Barley 


5.09 


4.39 


94.6 


81.7 


Oats 


4.54 


4.14 


119.2 


108.6 


Alfalfa l +§§ 


5.64 


4.48 


2.52 


2.00 


Alfalfa 2 §§ 


7.80 


5.31 


3.48 


2.37 


Alfalfa 3* §§ 


6.18 


4.12 


2.76 


1.84 


Wheat 


4.21 


3.94 


62.7 


58.7 


Sugar beets 3 


45.23 


37.95 


20.19 


16.94 


Alfalfa la + 


6.23 


5.31 


2.78 


2.37 


Alfalfa 2a 


8.53 


6.59 


3.81 


2.94 


Alfalfa 3a* 


7.80 


6.65 


3.48 


2.97 



*Barnyard manure at 33.5 t/ha to entire plot. 
+ ll-48-0 at 110 kg/ha to south half of plot. 
§Since 1923. 



§§ 



Since 1951. 



Sugar beets and alfalfa, the crops that receive the fertilizer, have 
benefitted substantially from it. A 110 kg/ha application of 
fertilizer has resulted in an average yearly increase of 7280 kg/ha of 
sugar beets. Similarly, the average increase for each of the 3-year 
alfalfa periods has been 4860 kg/ha. In addition, the benefits from 
the residual fertilizer are apparent in the yields of the cereal crops. 

The record crop yields from this rotation are as follows: barley, 
8623 kg/ha (160.4 bu/ac) ; hard red spring wheat, 4973 kg/ha (74.0 
bu/ac) ; oats, 6988 kg/ha (183.5 bu/ac); sugar beets, 62,966 kg/ha 
(28.11 tons/ac) ; and alfalfa, 14,067 kg/ha (6.28 tons/ac) . 

Five-year moving average yields and the cultivars grown for barley, 
oats, and wheat are shown in Figs. 1, 2, and 3, respectively. The 
increase in yield for barley has been greater than for either of the 



- 8 - 



other two cereals. The introduction of each new cultivar, with the 
exception of Jubilee, resulted in an increase in barley yield, and the 
cultivar Gait contributed most to the increased yield (Fig. 1) . 
Introduction of the new cultivars Eagle and Sioux increased the mean 
yields of oats (Fig. 2) . 

Only three hard red spring wheat cultivars, Red Fife, Marquis, and 
Thatcher, were grown during the first 60 years of the rotation. Mean 
yields increased with the introduction of Marquis, and Thatcher 
increased yields only slightly over those of Marquis. Utility wheats 
were grown during the last 10 years and their yields, especially those 
of Pitic, were substantially higher than those of the hard red spring 
wheats (Fig. 3) . 

Fig. 4 shows the 5-year moving average yields of sugar beets from the 
fertilized and unfertilized plots. Yields increased sharply during 
the first 10 years that sugar beets were grown (1923-1932) , and 
generally have climbed steadily since about the mid-1950' s. Similar 
data for third-year alfalfa are shown in Fig. 5. As explained earlier, 
alfalfa diseases depressed yields for three decades starting about 
1940. During the last decade, alfalfa yields improved dramatically. 

Increased crop yields can be attributed to several factors such as 
improved cultivars, better management, and improved soil conditions. 
Because some of these improvements occurred simultaneously, it is dif- 
ficult to establish the specific contribution of any individual factor. 

More detailed discussions on the yields of sugar beets and cereal crops 
were reported in 1976 and 1979, respectively, by Dubetz and Oosterveld. 

The rotation has apparently not suffered from a buildup of diseases 
other than those that plagued alfalfa, or from pests, weeds or harmful 
chemicals. Soil erosion has not been a problem. 



Soil analyses 

The changes in soil chemical properties with time are shown in 
Table 3. The pH of the surface soil increased gradually from 7.1 to 
7.6 during the first 60 years and appears to have stabilized. The pH, 
however, is still within the range for proper growth of all crops. 



- 9 - 



Table 3. Changes in soil chemical properties on Rotation U with time 
(means of ten plots) * 



1911 



1922 



1941 1951 



1961 



1971 



1981 



pH 



0-15 cm 
15-30 cm 
30-60 cm 
60-90 cm 



7.1 


7.2 


7.1 


7.5 


7.4 


7.6 


7.6 


7.3 


7.6 


7.2 


7.5 


7.5 
7.8 
8.0 


7.7 
7.8 
8.0 


7.7 

7.8 
7.8 



Organic matter (%) 



0-15 cm 
15-30 cm 
30-60 cm 
60-90 cm 



2.62 


2.16 


2.78 


2.75 


2.48 


2.30 


2.25 


1.50 


1.59 


2.25 


2.42 


2.08 


2.06 


2.07 








1.52 


1.16 


1.24 


1.20 








0.80 


0.64 


0.69 


0.73 



Nitrogen (%) 



0-15 cm 
15-30 cm 
30-60 cm 
60-90 cm 



0.18 


0.17 


0.19 


0.20 


0.21 


0.20 


0.20 


0.13 


0.14 


0.17 


0.18 


0.18 


0.17 


0.18 








0.11 


0.10 


0.10 


0.10 








0.07 


0.06 


0.06 


0.06 



Available phosphorus (ppm) 



0-15 cm - 


unfert. 


11 


16 


8 


11 


9 


10 


8 


- 


fert. 






8 


12 


12 


11 


15 


15-30 cm 




6 


7 


6 


8 


7 


6 


6 


30-60 cm 












3 


2 


2 


60-90 cm 












2 


2 


2 



Exchangeable potassium (ppm) 



0-15 cm 
15-30 cm 
30-60 cm 
60-90 cm 



375 


332 


342 


314 


283 


298 


306 


272 


200 


278 


238 


226 

112 

99 


200 
132 

111 


225 
132 
122 



♦Since 1941, means of 20 plots (north and south) , except available P for the 
0- to 15-cm depth, where means of ten plots (unfertilized and fertilized) 
are shown. 



-10 - 



After 70 years of cropping, the organic matter content in the 0- to 
15-cm layer of soil decreased from 2.62 to 2.25%, but that of the 15- 
to 30-cm depth increased markedly from 1.50 to 2.07%. These changes 
may be due in part to the dilution of the top layer with the lower 
layer through cultivation. However, the average organic matter content 
of the two layers showed an increase from 2.06% in 1911 to 2.16% in 
1981, which indicates that there was a net increase in the top 30 cm 
of soil. 

Total nitrogen increased slightly from 0.18% to 0.20% in the top 15 cm 
of soil but increased markedly from 0.13 to 0.18% in the 15- to 30-cm 
layer. This increase is attributed to the six years of alfalfa and to 
the application of barnyard manure. 

Available phosphorus has remained relatively low (10 ppm) in the 0- to 
15-cm depth of the unfertilized plots, but has increased to 15 ppm in 
the plots that receive fertilizer. The crops could probably benefit 
from larger applications of phosphorus fertilizer but continued moni- 
toring of crop yields and soil phosphorus will dictate any future 
action. 

Exchangeable potassium (K) decreased from 375 to 306 ppm in the 0-to 
15-cm layer and from 272 to 225 ppm in the 15- to 30-cm layer, but 
critical levels have not yet been reached. The results of analysis 
for total, exchangeable and extractable K were reported by Dubetz and 
Dudas (1981) . The total K content of this soil is relatively high 
(- 13,000 ppm in the 0- to 15-cm depth), and has changed little with 
time. Readily extractable K, derived from micaceous minerals and 
feldspars, remains relatively constant and apparently is being 
converted to exchangeable K at a rate that is sufficient to meet crop 
needs. 

Sampling of the additional soil depths, started in 1961 and in 1981, 
and the additional analysis (electrical conductivity) of all samples 
started in 1961, will provide new benchmarks for future comparisons. 



- 11 - 



References 

Association of Official Agricultural Chemists. 1970. Official 
Methods of Analysis. 11th ed. AOAC, Washington, D.C. 

Dubetz, S. 1954. The fertility balance in a ten-year sugar beet 
rotation after forty-two years of cropping. Proc. Amer. Soc. 
Sugar Beet Technol. 8: 81-85. 

Dubetz, S. and M. J. Dudas. 1981. Potassium status of a Dark Brown 
Chernozem soil after sixty-six years of cropping under irrigation. 
Can. J. Soil Sci. 61: 409-415. 

Dubetz, S. and M. Oosterveld. 1976. Effects of weather variables on 
the yields of sugar beets grown in an irrigated rotation for fifty 
years. J. Amer. Soc. Sugar Beet Technol. 19: 143-149. 

Dubetz, S. and M. Oosterveld. 1979. Sixty-six year trends in irri- 
gated crop yields - barley, wheat, and oats. Can. J. Plant Sci. 
59: 685-689. 

Hill, K. W. 1951. Effects of forty years of cropping under irri- 
gation. Sci. Agric. 31: 349-357. 

Olsen, S. R. , C. V. Cole, F. S. Watanabe, and L. A. Dean. 1954. 

Estimation of available phosphorus in soils by extraction with 
sodium bicarbonate. USDA Circ. 939. 

Peake, R. W. and M. W. Cormack. 1955. Effect of bacterial wilt on 
hay yield of irrigated alfalfa. Can. J. Agric. Sci. 35: 202-210. 

Walkley, A. and I. A. Black. 1934. An examination of the Degtjareff 
method for determining soil organic matter, and a proposed modifi- 
cation of the chromic acid titration method. Soil Sci. 37: 29-38. 



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CONVERSION FACTORS 






Approximate 






conversion 




Metric units 


factors 


Results in: 


LINEAR 








millimetre (mm) 


X 


0.04 


inch 


centimetre (cm) 


X 


0.39 


inch 


metre (m) 


X 


3.28 


feet 


kilometre (km) 


X 


0.62 


mile 


AREA 








square centimetre (cm 2 ) 


X 


0.15 


square inch 


square metre (m 2 ) 


X 


1.2 


square yards 


square kilometre (km 2 ) 


X 


0.39 


square mile 


hectare (ha) 


X 


2.5 


acres 


VOLUME 








cubic centimetre (cm^) 


X 


0.06 


cubic inch 


cubic metre (m^) 


X 


35.31 


cubic feet 


cubic metre (m3) 


X 


1.31 


cubic yards 


CAPACITY 








litre (L) 


X 


0.035 


cubic foot 


hectolitre (hl_) 


X 


22 


gallons 


hectolitre (hL) 


X 


2.5 


bushels 


WEIGHT 








gram (g) 


X 


0.04 


oz avdp 


kilogram (kg) 


X 


2.2 


lb avdp 


tonne (t) 


X 


1.1 


short tons 


AGRICULTURAL 








litres per hectare (L/ha) 


X 


0.089 


gallons per acre 


litres per hectare (L/ha) 


X 


0.357 


quarts per acre 


litres per hectare (L/ha) 


X 


0.71 


pints per acre 


millilitres per hectare (mL/ha) 


X 


0.014 


fl. oz per acre 


tonnes per hectare (t/ha) 


X 


0.45 


tons per acre 


kilograms per hectare (kg/ ha) 


X 


0.89 


lb per acre 


grams per hectare (g/ha) 


X 


0.014 


oz avdp per acre 


plants per hectare (plants/ ha) 


X 


0.405 


plants per acre 



630.72 
C759 
C 83-21 
OOAg 
c.3 



^Ten-year irrigated rotat.on U. 
19 11-1980 



LIBRARY BIBLIOTHEQUE 



AGRICULTURE CANADA OTTAWA K1A 0C5 

3 T073 DDD1117b 7